Contingent suppression of tolerance to the "anorexigenic" effect of haloperidol.

Whether tolerance develops to the "anorexia" induced by haloperidol (HAL) was determined. Rats were given HAL (2.5 or 5 mg/kg) either before or after access to milk for 53 days. Controls were given injections of saline. On Day 54, when all groups received pretest injections of the drug, only rats previously given posttest injections of HAL were tolerant. The absence of tolerance in rats previously given pretest injections suggests that tolerance is suppressed when rats are given access to food in the drugged state. It is concluded that tolerance develops to HAL as a result of pharmacological exposure but is suppressed by the "anhedonic" effect of the drug. The relevance of these findings to the role of reinforcement in behavioral tolerance is briefly discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Surface Morphology of Heat-Treated Ceramic Thin Films

The morphology of surfaces of several ceramic materials has been examined using transmission electron microscopy. The approach used was to prepare a sample for examination in the microscope, carefully clean it, and then heat-treat it. In the case of the oxides studied (alumina and spinel) the samples were heated in air; the non-oxides (α-SiC and β -SiC) were annealed under vacuum. The morphology in all but one case was such that the surface faceted parallel to the nearest low-index plane to give well-defined terraces; these were separated by ledges which also tended to facet parallel to the traces of low-index planes. The exception was the {1100} alumina surface, which appears to be unstable in air at temperatures close to 1400°C. A computer program using a multislice approach was used to estimate the height of the steps on the (0001) surface; the step heights appear to be multiples of the c lattice parameter. A reconstruction of this surface as a result of this heat treatment is also proposed.     

Nonnegative integral subset representations of integer sets

We consider an integer-subset representation problem motivated by a medical application in radiation therapy. We prove NP-completeness, derive nontrivial bounds, and report on the performance of a greedy heuristic.